1. Field of the Invention:
This invention relates to a liquid-sealed body mount, which is interposed between a cabin and a chassis frame of motor vehicles, especially motor trucks, to support them in a vibration insulating manner.
2. Description of Related Art:
There are known various body mounts of this type, and for example, a liquid-sealed body mount as illustrated in FIG. 5 is known from Japanese Patent First Publication 60-139942 ('85). The mount comprises an inner cylinder (1') and an outer cylinder (2'), two rubber members (3')(4') extending between both cylinders, an intermediate rubber plate member (5') partitioning the rubber members (3')(4') and extending between both cylinders (1')(2'), two liquid chambers (6')(7') enclosed on both sides of the intermediate rubber plate member (5'), an orifice (8') apertured in the intermediate rubber plate member (5') and communicating with both liquid chambers (6')(7') therethrough, and a liquid filled in both chambers (6')(7'). Another body mounts of similar structures are disclosed, for example, in Japanese Patent First Publications 62-188832 ('87) and 62-224744 ('87), which are depicted in FIG. 6 and FIG. 7, respectively.
With the known body mounts, under an unloaded condition after their assembly, the intermediate rubber plate member (5') intersects nearly orthogonally the inner and outer cylinders (1')(2') to take a horizontal orientation, which constitutes an unloaded neutral position.
On the other hand, when the mount so constructed is installed at a definite location of a motor vehicle and applied thereto with a rated load, thus being in a stationary state, the inner cylinder (1') is displaced to be depressed relatively to the outer cylinder (2') depending upon the magnitude of the load the inner cylinder (1') bears, which results in the state as shown in FIG. 5 in the broken lines. A deformation or deflection in the gravity direction, i.e., shearing direction is thus imparted to the mount in the stationary state.
If oscillations are transmitted to the vehicle body, in the state that such shear deformation is imparted to the mount, for bounding oscillations which cause to depress further the inner cylinder (1') side, the intermediate rubber plate member (5') is deviated slightly because of its small spring rate and consequently, vibration-damping effect due to the liquid flowing through both liquid chambers (6')(7') is not so significantly obtained whereas for rebounding oscillations, vibration-damping effect due to the flow of liquid is larger than that of the bounding oscillations because of a high spring rate. Hence, a problem with such body mount is that any equalized or balanced vibration-preventing characteristics against oscillations have not been achieved.
In order to solve the foregoing problem and drawbacks of known body mounts, this invention has been accomplished by providing the construction that a deformation in the shearing direction can be preliminarily imparted to an intermediate rubber plate member in the reverse sense to the direction in which loads are imposed on it so that the intermediate rubber plate member may be retained in the horizontal neutral state under conditions where a stationary load is applied.
Accordingly, it is an essential object of this invention to provide a body mount designed to exhibit balanced or equalized vibration-preventing characteristics on both bounding and rebounding sides thereby to reduce the oscillations on the cabin side of motor vehicles and improve the riding comfort.